Mourinho, twice sacked by Chelsea after three times winning the Premier League title, was embarrassed on his return in opposition as United imploded.

The United boss spoke at length to Conte at the final whistle, with suggestions the Portuguese had been annoyed that the Italian had encouraged the home support to cheer on the Blues when they were already 4-0 up.

Reports in Italian media said Mourinho told Conte: "You don't celebrate like that at 4-0, you can do it at 1-0, otherwise it's humiliating for us."

And the self-proclaimed Special One insisted the conversation should be private, despite choosing to conduct it in front of 41,000 people and the Stamford Bridge press box.

"I speak to Conte, I don't speak to you (the media)," Mourinho said.

"It was me and Antonio and stays with me and him. Unless he wants to share."

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"I've been a player too and I know how to behave," Conte told Sky Italia.

"I always show great respect for everyone, including Manchester United.

"There was no incident, it was just a normal thing to do. I wasn't mocking anyone, I wouldn't do that."

The Chelsea head coach added in his post-match press conference: "Today it was right to call our fans in a moment (when) I was listening (to) only the supporters of Manchester United, at 4-0.

"The players, after a 4-0 win, deserved a great clap. It's very normal.

"If we want to cut the emotion we can go home and change our job."

Mourinho's afternoon began with a warm embrace from Chelsea captain John Terry, again a substitute, while his presence in the opposition dugout was secondary for the home fans paying tribute to Matthew Harding, 20 years after his death in a helicopter crash.

Pedro's goal after 30 seconds was followed by a Gary Cahill goal, a fine Eden Hazard strike and a superb first Chelsea goal for N'Golo Kante.

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By then Chelsea fans were singing Mourinho's name as they once did, although this time it was in a mocking way.

Asked about the reception, Mourinho said: "I was in the game and I didn't feel it. For sure it was not negative, but no reason to be.

"What they have against me? What I have against them? Nothing."

Mourinho says he was pleased with United's performance, except for the defensive lapses.

"If we could delete the defensive mistakes, the globality (of the performance) was good," he said.

David Luiz, sold by Mourinho only to return two years later under Conte, might have seen red for a challenge on Marouane Fellaini, but the United boss refused to comment on it.

"After a defeat 4-0 if I'm going to speak about a referee, you (the media) are going to jump," Mourinho said.

"If I am going to be critical of a referee people will say, 'What are you doing?'

"If you think playing against 10 men for one hour, more or less, would be significant and could be an important change in the game, then you have to say it, you have to write it, but not me."

Conte downplayed the significance of the win and is already looking ahead to Wednesday' night's EFL Cup clash at West Ham.

He said: "The most important victory in my career (was) when I won the title, when I won a cup.

"When you win a battle, I prefer to win the war. A battle is not important.

"When you work very hard, then you win, it's important to celebrate.

"I have already told my players that United is the past and now we must be focused on Wednesday, because there is another tough game against West Ham."